The editosome for cytidine to uridine mRNA editing has a native complexity of 27S: identification of intracellular domains containing active and inactive editing factors

2002 ◽  
Vol 115 (5) ◽  
pp. 1027-1039 ◽  
Author(s):  
Mark P. Sowden ◽  
Nazzareno Ballatori ◽  
Karen L. de Mesy Jensen ◽  
Lakesha Hamilton Reed ◽  
Harold C. Smith
Keyword(s):  
Apolipoprotein B ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Catalytic Subunit ◽  
Cross Linking ◽  
Primary Hepatocytes ◽  
Mrna Editing ◽  
Apob Mrna ◽  
Rat Primary Hepatocytes

Apolipoprotein B mRNA cytidine to uridine editing requires the assembly of a multiprotein editosome comprised minimally of the catalytic subunit,apolipoprotein B mRNA editing catalytic subunit 1 (APOBEC-1), and an RNA-binding protein, APOBEC-1 complementation factor (ACF). A rat homolog has been cloned with 93.5% identity to human ACF (huACF). Peptide-specific antibodies prepared against huACF immunoprecipitated a rat protein of similar mass as huACF bound to apolipoprotein B (apoB) RNA in UV cross-linking reactions, thereby providing evidence that the p66, mooring sequence-selective, RNA-binding protein identified previously in rat liver by UV cross-linking and implicated in editosome assembly is a functional homolog of huACF. The rat protein (p66/ACF) was distributed in both the nucleus and cytoplasm of rat primary hepatocytes. Within a thin section, a significant amount of total cellular p66/ACF was cytoplasmic, with a concentration at the outer surface of the endoplasmic reticulum. Native APOBEC-1 co-fractionated with p66/ACF in the cytoplasm as 60S complexes. In the nucleus, the biological site of apoB mRNA editing, native p66/ACF, was localized to heterochromatin and fractionated with APOBEC-1 as 27S editosomes. When apoB mRNA editing was stimulated in rat primary hepatocytes with ethanol or insulin, the abundance of p66/ACF in the nucleus markedly increased. It is proposed that the heterogeneity in size of complexes containing editing factors is functionally significant and reflects functionally engaged editosomes in the nucleus and an inactive cytoplasmic pool of factors.

CUGBP2, a 54-kDa RNA-binding protein modulates apolipoprotein B mRNA editing by sequestering apobec-1 and ACF

2001 ◽  
Vol 120 (5) ◽  
pp. A103
Author(s):  
Shrikant Anant ◽  
Jeffrey O. Henderson ◽  
Debnath Mukhopadhyay ◽  
Susan Kennedy ◽  
Nicholas O. Davidson
Keyword(s):  
Apolipoprotein B ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Mrna Editing

scholarly journals Novel Role for RNA-binding Protein CUGBP2 in Mammalian RNA Editing

2001 ◽  
Vol 276 (50) ◽  
pp. 47338-47351 ◽  
Author(s):  
Shrikant Anant ◽  
Jeffrey O. Henderson ◽  
Debnath Mukhopadhyay ◽  
Naveenan Navaratnam ◽  
Susan Kennedy ◽  
...  
Keyword(s):  
Rna Editing ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Bovine Liver ◽  
Mrna Editing ◽  
Unbound Fraction ◽  
Apob Mrna ◽  
S 100

Mammalian apolipoprotein B (apoB) mRNA editing is mediated by a multicomponent holoenzyme containing apobec-1 and ACF. We have now identified CUGBP2, a 54-kDa RNA-binding protein, as a component of this holoenzyme. CUGBP2 and ACF co-fractionate in bovine liver S-100 extracts, and addition of recombinant apobec-1 leads to assembly of a holoenzyme. Immunodepletion of CUGBP2 co-precipitates ACF, and these proteins co-localize the nucleus of transfected cells, suggesting that CUGBP2 and ACF are boundin vivo. CUGBP2 binds apoB RNA, specifically an AU-rich sequence located immediately upstream of the edited cytidine. ApoB RNA from McA cells, bound to CUGBP2, was more extensively edited than the unbound fraction. However, addition of recombinant CUGBP2 to a reconstituted system demonstrated a dose-dependent inhibition of C to U RNA editing, which was rescued with either apobec-1 or ACF. Antisense CUGBP2 knockout increased endogenous apoB RNA editing, whereas antisense knockout of either apobec-1 or ACF expression eliminated apoB RNA editing, establishing the absolute requirement of these components of the core enzyme. These data suggest that CUGBP2 plays a role in apoB mRNA editing by forming a regulatory complex with the three components of the minimal editing enzyme, apobec-1, ACF, and apoB RNA.

CUGBP2, a 54-kDa RNA-binding protein modulates apolipoprotein B mRNA editing by sequestering apobec-1 and ACF

2001 ◽  
Vol 120 (5) ◽  
pp. A103-A103
Author(s):  
S ANANT ◽  
J HENDERSON ◽  
D MUKHOPADHYAY ◽  
S KENNEDY ◽  
N DAVIDSON
Keyword(s):  
Apolipoprotein B ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Mrna Editing

A novel 54-KDA AU-rich RNA binding protein in human intestine with a role in apolipoprotein B MRNA editing

2000 ◽  
Vol 118 (4) ◽  
pp. A186
Author(s):  
Jeffrey O. Henderson ◽  
Shrikant Anant ◽  
Jing Min ◽  
V.S. Sankaranand ◽  
Masahiro Oka ◽  
...  
Keyword(s):  
Apolipoprotein B ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Human Intestine ◽  
Mrna Editing

scholarly journals Ô‖Identification of GRY-RBP as an Apolipoprotein B RNA-binding Protein That Interacts with Both Apobec-1 and Apobec-1 Complementation Factor to Modulate C to U Editing

2000 ◽  
Vol 276 (13) ◽  
pp. 10272-10283 ◽  
Author(s):  
Valerie Blanc ◽  
Naveenan Navaratnam ◽  
Jeffrey O. Henderson ◽  
Shrikant Anant ◽  
Susan Kennedy ◽  
...  
Keyword(s):  
Apolipoprotein B ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein

scholarly journals The RNA-binding protein vigilin regulates VLDL secretion through modulation of Apob mRNA translation

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Mehrpouya B. Mobin ◽  
Stefanie Gerstberger ◽  
Daniel Teupser ◽  
Benedetta Campana ◽  
Klaus Charisse ◽  
...  
Keyword(s):  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Mrna Translation ◽  
Apob Mrna ◽  
Vldl Secretion

ApoB mRNA editing is mediated by a coordinated modulation of multiple apoB mRNA editing enzyme components

2007 ◽  
Vol 292 (1) ◽  
pp. G53-G65 ◽  
Author(s):  
Zhigang Chen ◽  
Thomas L. Eggerman ◽  
Amy P. Patterson
Keyword(s):  
Large Intestine ◽  
Rna Binding ◽  
Binding Protein ◽  
Critical Role ◽  
Regulatory Protein ◽  
Intestinal Cell ◽  
Mrna Editing ◽  
Apo B ◽  
Apob Mrna ◽  
Editing Enzyme

Apolipoprotein (apo)B mRNA editing is accomplished by a large multiprotein complex. How these proteins interact to achieve the precise single-nucleotide change induced by this complex remains unclear. We investigated the relationship between altered apoB mRNA editing and changes in editing enzyme components to evaluate their roles in editing regulation. In the mouse fetal small intestine, we found that the dramatic developmental upregulation of apoB mRNA editing from ∼3% to 88% begins with decreased levels of inhibitory CUG binding protein 2 (CUGBP2) expression followed by increased levels of apoB mRNA editing enzyme (apobec)-1 and apobec-1 complementation factor (ACF) (4- and 8-fold) and then by decreased levels of the inhibitory components glycine-arginine-tyrosine-rich RNA binding protein (GRY-RBP) and heterogeneous nuclear ribonucleoprotein (hnRNP)-C1 (75% and 56%). In contrast, the expression of KH-type splicing regulatory protein (KSRP), apobec-1 binding protein (ABBP)1, ABBP2, and Bcl-2-associated athanogene 4 (BAG4) were unaltered. In the human intestinal cell line Caco-2, the increase of apoB mRNA editing from ∼1.7% to ∼23% was associated with 6- and 3.2-fold increases of apobec-1 and CUGBP2, respectively. In the mouse large intestine, the editing was 48% and had a 2.7-fold relatively greater CUGBP2 level. Caco-2 and the large intestine thus have increased instead of decreased CUGBP2 and a lower level of editing, suggesting that inhibitory CUGBP2 may play a critical role in the magnitude of editing regulation. Short interfering RNA-mediated gene-specific knockdown of CUGBP2, GRY-RBP, and hnRNP-C1 resulted in increased editing in Caco-2 cells, consistent with their known inhibitory function. These data suggest that a coordinated expression of editing components determines the magnitude and specificity of apoB mRNA editing.

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